Embryology and Development 3 Flashcards
Describe how the amniotic cavity folds around the 3 germ layers (2 ways)
LATERALLY: sides fold in
MEDIALLY (in median plane): head and tail fold in
What day does amniotic folding begin?
day 20
Name 3 main sections of the gut & how they are shaped
median plane folds form the gut tube
HINDGUT
MIDGUT
FOREGUT
what structure of the urinary system are forming when medial folds begin?
ALLANTOIS
coelom
(see-loam)
little pockets of space of either side of neural tube that become body cavities
explain day 25 embryonic folding
- midgut fully forms
- oropharyngeal membrane attaches to foregut (will eventually become mouth)
- lateral folds start to pinch off yolk sac (tuns into YOLK STALK and yolk sac)
- ceolom gets larger
explain day 30 embryonic folding
- lateral fold fuse
- gut tube extends from cloacal to oropharyngeal membrane
- gut tube evaginations start to form organs (lungs, liver, pancreas, thyroid, pituitary gland, tonsils, auditory tubes)
- coelom fuses around heart to form pericardium
Which embryonic fold forms the gut tube?
lateral folds
How do limbs form? When do they begin to appear?
day 24-28
APICAL ECTODERMAL RIDGE: thickening of the ectoderm, stimulates outward growth
- grows structures proximal to distal
- blood supply formed first
- cartilage bone structure forms
How do the skeleton, muscles and nervous system form?
skeleton: from mesodermal or neural crest cells
muscle: from MYOBLASTS - derived from somites
nervous system: derived from neural tube and neural crest cells
how are myoblasts formed
from somites in the mesoderm
thickening ectoderm to form lib bud is called
APICAL ECTODERMAL RIDGE
How are the body cavities formed? In what order?
Coelom enlargement forms:
pericardium forms
pleura forms
trunk cavities separate
What is an evagination?
outward projection of an organ or structure
what organs are apart of gut tube evaginations (day 30)
lungs, liver, pancreas, thyroid, pituitary gland, tonsils, auditory tubes
